I use an encrypted RoamResearch graph. I used to be able to paste images in and they would be uploaded and encrypted. Today this functionality stopped working and my graph's images wouldn't load. I quickly realized why.
The Solution
Your network is blocking access to firebasestorage.googleapis.com
My Situation
The previous night I was updating my wifi router settings and enabled ad blocking. Today I noticed the image issue. I hopped back to my router settings and added the above URL to my allow rules and I'm back up and running.